Driving mechanisms having multiple maltese driving gear

ABSTRACT

A multiple maltese driving mechanism for the conversion of the continuous rotation of a driving shaft into the stepwise movement of a body, said mechanism comprising a plurality of toothed members fixed to said body and a plurality of driving pins fixed to said driving shaft, said pins being adapted to cooperate in pairs with pairs of said members for special steps of said body and during such steps to drive said body by turns and to keep together said body positively coupled with said driving shaft.

United States Patent [191 Van Riemsdijk DRIVING MECHANISMS HAVINGMULTIPLE MALTESE DRIVING GEAR [75] Inventor: Gerardus Andriaan VanRiemsdiik,

Nijmegen, Netherlands [73] Assignee: Smit Niimegen ElectrotechnischeFabrieken, Nijmegen, Netherlands [22] Filed: Dec. 5, 1972 [211 Appl.No.: 312,260

[30] Foreign Application Priority Data Dec. 15, 1971 Netherlands 71171777 52 us. Cl. 74/436 [51] Int. Cl. F16h 55/04 [58] Field of Search 74/436[56] References Cited UNITED STATES PATENTS 3,485,965 12/1969 Bleibtreuet al. 74/436 X [451 June 25, 1974 3,597,559 8/1971 Van Riemsdijk 74/436X Primary ExaminerLeonard H. Gerin Attorney, Agent, or Firm-Snyder,Brown and Ramik [57] ABSTRACT A multiple maltese driving mechanism forthe conversion of the continuous rotation of a driving shaft into thestepwise movement of a body, said mechanism comprising a plurality oftoothed-members fixed to said body and a plurality of driving pins fixedto said driving shaft, said pins being adapted to cooperate in pairswith pairs of said members for special steps of said body and duringsuch steps to drive said body by turns and to keep together said bodypositively coupled with said driving shaft.

2 Claims, 9 Drawing Figures PAIENIEDJUNZSIEITI 3818.747

SHEET 2 BF 2 1. DRIVING MECHANISMS HAVING MULTIPLE MALTESE DRIVING GEARThe invention relates to a driving mechanism provided with a multiplemaltese driving gear for the stepwise movement of a body, e.g. thestepwise rotation of a shaft, by means of a rotating driving shaft, inwhich the body to be driven comprises at least one pair of rigidlyinterconnected toothed members which are positioned side by side or oneabove the other in the direc tion of the driving shaft and extendtransversely to said shaft, said toothed members overlapping each otherat least partly in the direction of movement; in which the driving shaftis provided with at least one pair of driving pins, of which each one isadapted to cooperate with an individual one of said toothed membersonly, said driving pins being disposed at different radial distancesfrom said driving shaft and extending parallel to said shaft in one andthe same plane containing said shaft;

in which each one of the overlapping portions of said toothed membershas at least one tooth space and in which the tooth spaces of saidoverlapping portions form at least one pair of associated tooth spaces,of which the central lines lie in one and the same plane extendingtransversely to the direction of movement of the body.

A maltese driving mechanism of this kind for the stepwise rotation of ashaft, particularly the shaft of an on-load tap-changer for a regulatingtransformer, is disclosed in the Swiss Patent specification 434,450.This known maltese driving mechanism is used for the stepwise rotationof a tap selector over two different angles, said tap selector beingadapted to operate under noload contitions only. Therein the rotationover the larger angle is necessary in the region, where the voltagedifference between two adjacent fixed contacts of the tap selector is amultiple of the voltage difference between the other adjacent fixedcontacts. In this known driving mechanism the speed of switching duringthe rotation over the larger angle is greater than that during therotation over the smaller angle. This difference of speed does not raisedifficulties in a tap selector operating under no-load conditions, sinceno switching arc is produced during the change-over movement in such atap selector. However it has appeared, that said difference of speed isdisadvantageous in selector switches operating under load conditions,since therein the switching are produced during the change-overoperation over the larger angle, said are disappearing at the zerotransition of the current, that means at the most half a cycle after ithas been started, is not extinguished until the movable contact, onwhich the switching arc is established, has almost reached the nextfixed contact of the switch. Then the rise is great that the switchingarc jumps to the next fixed contact and thereby produces ashort-circuit.

The invention has the object to provide a driving mechanism with amultiple maltese driving gear, in which the mentioned disadvantage isavoided and by means of which a body can not only rectilinearly movedwith different steps or rotated over different angles but also the curveof the speed of said body .can be chosen at wil within a predeterminedzone during its movement. Consequently, a driving mechanism according tothe invention has more degrees of freedom than the known drivingmechanism, whereby it is possible to make, for instance, the maximumspeed during the greater step equal to that during a smaller step.

According to the invention this is achieved in that the tooth spacesformed in the overlapping portions of such a pair of toothed members andforming a pair of tooth spaces belonging to each other have such shapesthat the driving pins engaging said tooth spaces during the stepwisemovement of the body drive said body at least by. turns and the body is,during said movement, positively coupled with the driving shaft by turnsby one driving pin, and by the two driving pins together. Thus,

. in that case both driving pins act, during one movement of the body,on the toothed members of said body. If one driving pin is used for thegreater step and the other one for the smaller step of the body, thespeed of the body can during the movement thereof by both driving pins,be varied in the region lying between the region of speed depending onthe action of one driving pin and the region of speed depending on theaction of the other driving pin. The curve of the speed then depends onthe shape ofeach one of the tooth shapes cooperating to effect themovement in question.

By a positive coupling between the body and the driving shaft isunderstood such a coupling, that in each angular position of the drivingshaft only one single position of the body is possible.

In the mechanism constructed according to the invention said positivecoupling is obtained, in that through a portion of the stroke onedriving pin engages in the known way a fitting slot left between theteeth of one toothed member and through a next portion of the stroke oneof both driving pins is used for driving and the other driving pin locksthe position of the body relatively to that of the driving shaft. Thedriving pins may alternately have a driving and a locking function. Howthey cooperate depends on the shapes of the tooth spaces of the toothedmembers of said body.

The invention is not restricted to the use of one pair of toothedmembers and one pair of driving pins cooperating therewith. If, forinstance, the driving shaft is provided with three driving pins lying atdifferent radial distances from said shaft and the body is provided withthree toothed members belonging thereto, three different pairs ofdriving pins and pairs of toothed members can be formed for moving thebody with different steps and speeds, so that, when the driving pins canalso be active by themselves only as in the known mechanisms, the bodycan be moved with steps of three different lengths and with sixdifferent curves of the speed. The driving mechanism constructedaccording to the invention and used for driving an on-load tap-changerfor a regulating transformer may advantageously be so carried out, thatof the tooth spaces formed in the overlapping portions of such a pair oftoothed members and forming a pair of tooth spaces belonging to eachother the tooth space of the toothed member cooperating with the drivingpin which is closest to the driving shaft has a substantially triangularshape and the other tooth space has the shape of a bottle.

The invention will be further elucidated with the aid of the drawing.Therein are:

FIG. 1 partly a cross sectional view and partly a plan view of a maltesedriving gear constructed in accordance with the invention",

FIG. 2 partly an axial sectional view on the line [1-H and partly anelavational view of the driving mechanism shown in FIG. 1,

FIGS. 3 and 4 different positions duringa step of the driving mechanismshown in FIG. 1,

FIG. a diagrammatical view of an on-load tapchanger, in which thedriving mechanism illustrated in FIGS. l4 may be used,

FIG. 6 partly a cross sectional view and partly a plan view of a variantof the maltese driving mechanism shown in FIGS. 1-4,

FIG. 7 partly an axial sectional view and partly an elevational view ofthe driving mechanism shown in FIG.

FIG. 8 partly a cross sectional view and partly a plan view of a secondvariant of the driving mechanism shown in FIGS. l4 and FIG. 9 a detailof a third variant of the driving mechanism shown in FIGS. l4.

Although the drawing only shows maltese driving gear for thetransmission of a continuous rotary movement into a stepwise rotation itwill be obvious that such driving mechanisms can also be used for thetransmission of a continuous rotary movement into a stepwise rectilinearmovement. For the latter case a maltese toothed rack instead of amaltese toothed disc is used.

In FIGS. l4 a continuously rotating driving shaft is designated by l anda stepwise rotating driven shaft is indicated by 2. Mounted on thedriven shaft 2 are a toothed member in the shape of a disc 3 and,axially spaced therefrom, a toothed member in the shape of a sector 4.The toothed disc 3 has eight tooth spaces, of which six consecutivetooth spaces 5 lie at equal smaller angular distances from each otherand the two remaining tooth spaces 6 lie at greater angular distancesfrom each other and from the tooth spaces 5. The toothed sector 4 hastwo tooth spaces 7, the centre line of each of which extends in the sameplane containing the driven shaft 2 as the centre line of a tooth space6 of the toothed disc 3. A driving pin 8 cooperates with the tootheddisc 3 and a driving pin 9 cooperates with the toothed sector 4. Thedriving pins 8 and 9 extend parallel to the driving shaft 1 in one andthe same plane containing said shaft 1. The driving pin 8 lies closer tothe driving shaft 1 than the pin 9.

The shape of the tooth space 6 of the disc 3 is substantially triangularand the tooth space 7 has the shape of a bottle.

If the shaft 2 is rotated with its toothed sector 4 out of reach of thedriving pin 9, the stepwise rotation of the shaft 2 is determined onlyby the cooperation of the pin 8 and one of the tooth spaces 5 of thedisc 3. The shaft 2 is then rotated over the smaller angles. However, assoon as the toothed sector 4 has been brought into reach of the pins 9and 8, as is shown in FIG. 4, the pin 9 engages the neck of thebottle-shaped tooth space 7 of the toothed sector 4. The driving pin 8penetrates at the same time into the V-shaped tooth space 6 of the disc3, but it remains yet clear from the left-hand tooth flank bounding thespace 6. The shaft 2 is then first driven by the pin 9 over a smallangle. However, as soon as said pin has left the neck of thebottle-shaped tooth space 7 the driving pin 8 comes into contact withthe mentioned tooth flank and the shaft 2 is driven, as is shown in FIG.3, through the disc 3 by the pin 8. But the pin 9 comes into contactwith the right-hand flank of the bottle-shaped tooth space 7 at the verymoment, at which the pin 8 takes over the driving of the shaft 2 fromthe pin 9 (FIG. 3). Owing thereto the shaft 2 is positively coupled withthe shaft 1, since, notwithstanding the V-shaped tooth space 6 and thebottle-shaped tooth space 7 are each too wide to lock the driving pin 8and 9, respectively, the two pins are active together and prevent thatthe shaft 2 with the toothed members 3 and 4 can have more than oneangular position relatively to each active angular position of thedriving pins 8 and 9.

After the pin 9 has left the neck of the bottle the shaft 2 is driven bythe driving pin Sand the disc 3 only, till the centre position shown inFIG. 1 has been reached. This means that at passing said centre positionthe angular speed of the shaft 2 is equal to the maximum angular speedwhich occurs, when the driving pin 8 cooperates with one of the radialslots 5 of the disc 3. However, as soon as the centre position shown inF IG. 1 has been passed, the pin 9 becomes the driving pin and the pin 8sees together with the pin 9 to the positive coupling between the shaft1 and 2. Near the end of the stroke the pin 9 penetrates into the neckof the bottle again and the pin 8 leaves the driven flank of the toothspace 6 of the disc 3, so that the shaft 2 is yet driven by the pin 9only. Finally both pins leave the respective tooth spaces and thestepwise rotation has come to an end.

In the described multiple maltese driving gear the two driving pins 8, 9act by turns as driving pin and the pin 9 sees to the positive couplingbetween the shafts l and 2, as long as it is in the bottle neck duringthe first and the last part of the active stroke, whereas in theintermediate part of said stroke the pins 8 and 9 see together to saidpositive coupling. What will happen in the second half of the activestroke can be understood from FIGS. 3 and 4, if the direction ofrotation indicated by the arrow is reversed.

It will be apparent that, when the toothed disc 3 and the toothed sector4 on one hand and the driving pins 8 and 9 on the other hand cooperatefor the stepwise rotation of the shaft 2, said shaft is rotated over alarger angle. Said angle is defined by the radial distance of the pin 9from the driving shaft 1. The other steps are smaller, as they aredefined by the smaller distance between the pin 8 and the driving shaft1.

The driving mechanism shown in FIGS. 1-4 is adapted for a selectorswitch illustrated in FIG. 5. This selector switch comprises eight fixedcontacts which are arranged at equal free distances from each other. Ofthese fixed contacts the contacts 10, ll, 12, 13, 14 extend throughequal smaller lengths of arc and the contacts 15 and 17 extend eachthrough a somewhat greater length of arc, whereas the contact 16 has alength of are which is still a bit greater. For the changeover operationof the integral group of rotatable contacts 18, 19, 20 from the fixedcontact to the fixed contact 17 said group must be rotated over a largerangle than for the change-over operation between ad jacent contacts ofthe series of fixed contacts l7, l0, 11, 12, 13, 14, 15. It is acondition in this selector switch that, when the group of rotatablecontacts 18, 19, 20 passes the intermediate position between two fixedcontacts, the angular speed, that means the maximum angular speed, hasalways the same smaller value. This condition is satisfied by thedriving mechanism shown in FIGS. 1-4, as during passing saidintermediate position only pin 8 is active, so that then the angularspeed is independent of the fact, whether the driven shaft 2 is drivenone further step through a smaller or a larger angle.

In the variant illustrated in FIGS. 6 and 7 of the driving mechanismshown in FIGS. l-4 the driving shaft is provided with three driving'pins21, 22 23 lying at different radial distances from said shaft in acommon plane containing the driving shaft 1 and the driven shaft 2comprises three toothed members 24, 25, 26 cooperating with said drivingpins. In FIG. 6 the pin 23 starts to drive the shaft 2 through thetoothed sector 26. Thereafter the pin 22 and the toothed disc take overthis driving action. During this driving action the stroke is defined bythe pin 23 and the maximum angular speed is defined by the pin 22 only.

During the next revolution of the driving shaft 1 the driving pin 21 and22, the sector 24 and the disc 25 come. into action. The angulardisplacement of the shaft 2 is then detennined by the pin 21 and themaximum angular speed by the pin 22. After the toothed sectors 26 and 24have been active, the further rotation of the shaft 2 is carried out bythe pin 22 and the disc 25 only. Therefor the rest of the disc 25 has inthe normal manner radial slots 27.

In that case it is also possible to let the driving pins 21 and 23cooperate, if to that and the shaft 2 is provided with a suitabletoothed sector. Further more it is possible to reverse the actions tothe cooperating driving pins when the tooth spaces are given suitableshapes to that end, so that the maximum angular speed is determined bythe pin lying furthest from the driving shaft and the step is defined bythe pin lying closest to said shaft.

In the variant shown in FIG. 8 all steps of the driven shaft 2 areequal, since the angular displacement is determined by the driving pin28 lying furthest from the driving shaft 1. Only through two adjacentangles the shaft 2 is driven by the driving pins 28, 29, the tootheddisc 30 and the toothed sector 31. During the movement through theseangles the driving pin 29 sees to the reduction of the maximum angularspeed.

Finally FIG. 9 shows a detail, in which the shapes of the cooperatingtooth spaces differ from those of the driving mechanisms illustrated inthe preceding figures. Therein the flanks of the triangular tooth spaces32 are bent inwards and the shape of the bottle-shaped tooth space 33 ismore cambering. It will be obvious that another shape of the flanks of atooth space will correspond, during the step wise rotation or thestepwise rectilinear movement, with another curve of the speed.Furthermore it is observed that the two flanks of a tooth space need notbe the mirror images of one another.

What I claim is:

l. A driving mechanism provided with a multiple maltese driving gear forthe stepwise movement of a body, e.g. the stepwise rotation of a shaft,by means of a rotating driving shaft, said driving mechanism comprisingat least one pair of toothed members which are rigidly connected to saidbody and extend in different planes at right angles with said drivingshaft, said toothed members overlapping each other at least partly inthe direction of movement of the body and at least one pair of drivingpins rigidly connected to the driving shaft and extending parallel toand at different radial distances from the driving shaft in one and thesame plane containing said shaft, each one of said driving pins beingadapted to cooperate with an individual one of said toothed membersonly, each one of the overlapping portions of said pair of toothedmembers having at least one tooth space, of which the centre line liesin the same plane extending transversely to the direction of movement ofthe body as the centre line of an associated tooth space of the othertoothed member of said pair and the two associated tooth spaces of theoverlapping portions of said pair of toothed members having such shapes,that during its stepwise movement the body is driven at least by turnsby the driving pins engaging said associated tooth spaces and is heldpositively coupled with the driving shaft by turns by one of saiddriving pins and by both driving pins together.

2. A driving mechanism as claimed in claim 1, in which of the twoassociated tooth spaces of the overlapping pinions of the pair oftoothed members the one of the toothed member cooperating with thedriving pin which is closest to the driving shaft has a substantiallytriangular shape and the other one has the shape of a bottle.

1. A driving mechanism provided with a multiple maltese driving gear forthe stepwise movement of a body, e.g. the stepwise rotation of a shaft,by means of a rotating driving shaft, said driving mechanism comprisingat least one pair of toothed members which are rigidly connected to saidbody and extend in different planes at right angles with said drivingshaft, said toothed members overlapping each other at least partly inthe direction of movement of the body and at least one pair of drivingpins rigidly connected to the driving shaft and extending parallel toand at different radial distances from the driving shaft in one and thesame plane containing said shaft, each one of said driving pins beingadapted to cooperate with an individual one of said toothed membersonly, each one of the overlapping portions of said pair of toothedmembers having at least one tooth space, of which the centre line liesin the same plane extending transversely to the direction of movement ofthe body as the centre line of an associated tooth space of the othertoothed member of said pair and the two associated tooth spaces of theoverlapping portions of said pair of toothed members having such shapes,that during its stepwise movement the body is driven at least by turnsby the driving pins engaging said associated tooth spaces and is heldpositively coupled with the driving shaft by turns by one of saiddriving pins and by both driving pins together.
 2. A driving mechanismas claimed in claim 1, in which of the two associated tooth spaces ofthe overlapping pinions of the pair of toothed members the one of thetoothed member cooperating with the driving pin which is closest to thedriving shaft has a substantially triangular shape and the other one hasthe shape of a bottle.